2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...

Bolsa Chica Lowlands Restoration Monitoring
2008 Annual Report
represented by juvenile size classes, demonstrating the linkages between the basin and coastal
fisheries, and the role of the basin as nursery habitat for spawning or post-larval dispersal.
The Bolsa Chica Steering Committee has decided to conduct an additional year of fisheries monitoring
in Year 3, which was initiated in October 2008 and will extend through July 2009. The next
monitoring is then scheduled to occur in Year 5, with sampling events in October 2010, and January,
April, and July 2011.
BENTHIC COMMUNITY
Assessments of benthic infauna and epifauna were conducted in January and July 2008 at three stations
in the FTB. To sample the benthic infauna, three replicate sediment cores were collected from the
+0.3-m (+1-foot) NAVD elevation and from the -0.6-m (–2-foot) NAVD elevation and rinsed through
a 1.0-mm sieve. Organisms from each sample were transported to the laboratory to be identified to the
lowest practical taxonomic level, counted, and weighed. Epibenthic invertebrates were assessed using
1-m 2 quadrat at each of the sampling points and tidal elevations. All epifaunal organisms were
identified and counted. Additionally, during the completion of fish studies described above, the
incidental by-catch of epibenthic invertebrates was collected, identified, and counted to further
enhance the detection of epibenthic organisms.
As expected, considerable variability was observed in the infaunal invertebrate community due to the
limited replication and frequency of sampling, variations in sediment type within and between stations,
and the patchiness that is characteristic of benthic invertebrate communities in general. However, the
two sampling events during the second year post-restoration did serve to document that the creation of
the FTB has provided benthic food resources available to birds, fish, and other invertebrates. The
created basin was found to support nine phyla of infauna, with polychaetes the dominant taxa (61% of
the total), followed by tanaids and bivalves (21% and 4% of the total, respectively). Benthic
monitoring conducted during the comparable second year post-restoration at Batiquitos Lagoon (1998)
found the density of infauna there to be very similar, indicating the FTB is performing as expected for
a created tidal embayment.
The quadrat sampling to characterize epibenthic communities did not provide a good representation of
the invertebrates present. Most epibenthic organisms are highly mobile and had vacated the mudflat
shoreline during the low tides targeted for the survey work. However the tracking of epibenthic
invertebrates in the fishing gear documented considerably more diversity due the greater area and
depth range sampled. Species seen in high numbers in 2008 were the pink shrimp Pandalus sp., the
small kelp humpback shrimp (Hippolyte clarki) commonly associated with eelgrass, various tunicates,
B. gouldiana, and Argopecten ventricosus. Six non-native species were identified, including the
Japanese mussel (Musculista senhousia), a highly invasive non-native mussel present in many
California bays and estuaries and detected during the first biological monitoring event in October
2007.
Epibenthic invertebrates present after the opening of the basin to tidal influence were all marine
species associated with estuarine or bay environments. It is expected that the species list will continue
to expand over time as additional sampling is conducted. These macroinvertebrates also provide an
important prey base for fish and birds in the basin.
Merkel & Associates, Inc. 3